20.03.2021 12:32, Patrik Janoušek wrote:
Current implementation of dirty bitmaps for raw format is very
limited, because those bitmaps cannot be persistent. Basically it
makes sense, because the raw format doesn't have space where could
be dirty bitmap stored when QEMU is offline. This patch solves it
by storing content of every dirty bitmap in separate file on the
host filesystem.
However, this only solves one part of the problem. We also have to
store information about the existence of the dirty bitmap. This is
solved by adding custom options, that stores all required metadata
about dirty bitmap (filename where is the bitmap stored on the
host filesystem, granularity, persistence, etc.).
Signed-off-by: Patrik Janoušek<p...@patrikjanousek.cz>
Hmm. Did you considered other ways? Honestly, I don't see a reason for yet
another storing format for bitmaps.
The task could be simply solved with existing features:
1. We have extenal-data-file feature in qcow2 (read docs/interop/qcow2.txt).
With this thing enabled, qcow2 file contains only metadata (persistent bitmaps
for example) and data is stored in separate sequential raw file. I think you
should start from it.
2. If for some reason [1] doesn't work for you, you can anyway use an empty qcow2 file to
store bitmaps instead of inventing and implementing new format of bitmaps storing. (Same
as your approach, you'll have a simple raw node, and additional options will say
"load bitmaps from this qcow2 file". But for such options we'll need good
reasons why [1] isn't enough.
--
Best regards,
Vladimir
